I have not taken admin law but I am writing a memo for another class on a federal agency's options for adopting a new department policy. I know this can be done through memos (i.e. department head/secretary writes a memo directing department employees to do or not do something), but memos can also be easily rescinded by the next administration, so I want to discuss options that could have a more lasting effect as well. I vaguely know that the APA is a thing that mandates a more involved process when an agency wants to make a more permanent rule. Can anyone give me a short primer on the APA and the process for an agency to adopt a new rule - or direct me to a good source that gives an overview of the process?

I know this is kind of a ridiculous question since this is the subject of an entire semester's worth of class, so I'm not looking for a super detailed answer, just something that will make me not look like an idiot.